Reland "Bump the global default C standard to gnu23."

This reverts commit f572de9843a1c6510579d95d0812624d3feb04f3.

Change-Id: I1926ee7fe96983d8902a3d9e3d7598f96c22bf07
diff --git a/cc/cc_test.go b/cc/cc_test.go
index 98af7b6..2be4e48 100644
--- a/cc/cc_test.go
+++ b/cc/cc_test.go
@@ -2689,7 +2689,7 @@
 	cppOnly := []string{"-fPIC", "${config.CommonGlobalCppflags}", "${config.DeviceGlobalCppflags}", "${config.ArmCppflags}"}
 
 	cflags := []string{"-Werror", "-std=candcpp"}
-	cstd := []string{"-std=gnu17", "-std=conly"}
+	cstd := []string{"-std=gnu23", "-std=conly"}
 	cppstd := []string{"-std=gnu++20", "-std=cpp", "-fno-rtti"}
 
 	lastNDKFlags := []string{